This invention concerns a rotary burner. To be more exact, the rotary burner according to the invention is applied to heating furnaces, temperature maintaining furnaces, and electric arc furnaces, whether they be melting furnaces or reduction furnaces, in the melting step or in the refining step so as to provide an additional contribution of heat.
The rotary burner according to the invention enables thermal energy to be applied to the so-called cold areas of the furnace, that is to say, to wide areas of a controlled and controllable extent, and at the same time creates a remixing of the gases, vapours and air in the environment.
Burners of the state of the art generally consist of conduits fed with a gaseous or gasified combustible substance and with an oxidizer substance such as combustion-supporting oxygen under pressure, for instance.
Depending on the positioning of these conduits, the burners can be of a type producing parallel currents, inclined currents, swirling currents or distributed currents.
The two currents, possibly pre-mixed, of a combustible substance and oxidizer meet in the vicinity of the outlet of the burner, where the combustion takes place.
Various types of burners have been disclosed but entail a series of drawbacks which have not been overcome:
a) burners with a concentrated flame, which are solidly fixed to the furnace and involve the shortcoming of providing a low thermal yield since they affect only a limited area of the furnace; PA1 b) burners with a wide flame, which are solidly fixed to the furnace and entail the disadvantage of requiring a complex flushing of the nozzles to keep the latter clean even when the burners are quenched; PA1 c) burners with a concentrated or wide flame, which can be removed from the furnace and be positioned as desired; their introduction into and removal from the furnace take place through an appropriate aperture; the main disadvantage is the difficulty in keeping this aperture free; PA1 d) burners with a concentrated flame, which can be oriented by means of a cylindrical joint; this type of joint enables the burners to be oriented substantially along a straight line.
IT-UD92A000009 discloses a burner fitted to a positioning assembly cooperating with a fixture assembly solidly fitted to the shell of a melting furnace.
The positioning and fixture assemblies define a ball-and-socket joint which enables the burner to be positioned on a first plane and to be oriented on a second plane perpendicular to the first plane. This teaching does not overcome the problems of a correct, determined directing of the flame within the furnace, nor does it define the areas of the furnace to be lapped nor the parameters by which the burner can be oscillated and oriented.
A typical employment of these burners is with electric arc furnaces, whether the latter operate with indirect heating (arc melting furnaces) or direct heating (arc reduction furnaces). The burners are arranged at least on the sidewalls of the furnace.
The burners are generally placed at a given height above the level of the molten metal and are downwardly inclined towards the molten metal by a desired angle, which is generally, but is not restricted to, between 25.degree. and 60.degree..
These auxiliary burners are employed mostly to heat the areas generally near the sidewalls of the furnace and in the space between the electrodes, where the action of the electrodes is delayed and less effective and therefore generally requires additional time to melt the scrap located there.
The shortcomings of the above burners do not enable an effective working of the burners to be ensured in association with such arc furnaces and therefore lead to a low yield, difficulties of working and maintenance, complexities of installation and handling and still other problems.